Block signaling system for railroads



Oct. 26, 1937. R. M. PHINNEY BLOCK SIGNALING SYSTEM FOR RAILROADS Filed Aug. 16, 1955 2 Sheets-Sheet 1 BY WP? J;

J2 mm I: In a U H. n g 3 mm H H mm 2 L mm ATTORNEY R. M. PHINNEY BLOCK SIGNALING SYSTEM FOR RAILROADS Oct. 26, 1937.

Filed Aug. 16, 1935 2 Sheets-Sheet 2 Patented Oct. 26, 1937 UNITED STATES BLOCK SIGNALING SYSTEM RAILROADS Robert M. Phinney, Rochester, N. Y., assignor to General Railway Signal Company, R ochester, i

Application August 16, 1935, Serial- No. 36,481

12 Claims. (01.246-33) This invention relates to block signaling systems for single track railways, and more particularly to such a system of the type known as an absolute permissive block system.

In an absolute permissive block signaling system, the portions of single track between passing sidings are signaled for either direction of traffic, and the same facility and protection for trains following each other through the portions of single track is provided as in a modern signaling system for one direction of traflic only, but trains are prevented from entering the single track portions already occupied by a train or trains moving in the opposite direction. In the usual absolute permissive block system, a series of signal controlling relays associated witheach direction of traffic are controlled in tumble down or repeater fashion so that a train entering one end of the single track portion causes the series of signal controlling relays associated with the opposite direction of trafiic to tumble down to the other end of the single track portion thereby causing all opposing signals to display a stop indication, and directional stick relays are selected in accordance with the direction of a train progressing through the single track portion which afifect the signal control relays associated with the same direction of trafiic in the manner to permit following train movements.

In railway signaling systems, it is essential that all circuits and apparatus should be energized to provide a clear signal indication, as a failure of the energy source, a broken wire or the like then results in a restrictive signal indication thus providing maximum safety of train operation in the event of a failure of signal apparatus or circuits. Consequently in an absolute permissive block signaling system, it is usually necessary to provide signal controlling relays, line circuits and the like which are normally maintained energized while a train is not passing through the associated portion of the railway system in order that upon the entrance of a train, the series of signal controlling relays can be tumbled down or successively deenergized with certainty to affect a stop indication at opposing signals. It will therefore be evident that energy is required in such normally energized systems for the signals and their controlling apparatus at all times except when a stop indication is being displayed, and when primary or storage batteries are employed, it is high- -ly desirable to reduce such energy consumption to a minimum. i

In signaling systems employing semaphore wayside signals, a severe sleet'storm or freezing known as passing sidings.

rain may prevent movement of the semaphore arm. Consequently in a signaling system wherein the signals normally display a clear indication,

the semaphore arms assume a clear position throughout the majority of the time, 50131134731115 abnormal condition usually prevents movement of the semaphore arm from its clear positionand I be over "an unsafe section of track.

In view of the above and other considerations, it is proposed in accordance with the present inventio-n'to provide an absolute permissive block signaling system wherein the energy consumed is reduced to a minimum and yet which affords the usual protection and facility for train movements. More specifically, it isproposedto provide an absolute permissive block signaling system wherein the wayside signals, the signal control relays and line circuits or all the apparatus with the exception of the usual track circuitsare normally deenergized while a train is not approaching or traversing the associated portion of the railway system, and which is initiated into operation by an approaching train to provide equal facility and a clear indication then exists which possibly may the same degree of signal protection for such train movements as is provided by the usual normally energized systems. It is further proposed to provide a signaling system havingthe advantages attributed to'signals wherein a restricted indication is normally displayed when a train is .30 not approaching such signals. Other objects, purposes and characteristic features of the present invention will be apparent as the description thereof progresses, during which ,referencesvwill be made to the accompanying 35 drawings, in which:

Fig; 1 and Fig. 2 show in adiagrammatic and conventional manner one embodiment of the present invention applied to a portion. of a railway system. These-two figures show adjacent {.40 portions of .railwaytrack andare intended to be placed end'to end with Fig. 2 at the right.

The portion of the railway systemshown in the accompanying drawings is dividedby insulating joints J into sections or blocks I through 1, the blocks 2 and 6 including double track or what is In describing the present invention, the apparatus having like functions at the different locations or blocks have been given the same reference letter or letters with a preceding numeral corresponding to the reference number of the associated block. In order to simplify the present disclosure, the sig-. nal controlling apparatus and-circuits have been shown in, detail for one direction of traflic only,

Well recognized.

east bound signals 2SG, 3S6, ISG, 55G, BSG and 'ISG, respectively. Also, the west bound signals I3SG, MSG and I5SG are controlled by back contacts of stick relays 5S, 4S and 38 respectively, as the east bound signals 3SG, ISG and 58G are controlled by back contacts 41, 36 and of. stick relays MS, MS and I3S, respectively;

A track circuit of the usual normally energized type is provided at each blockby .a'batter-y B at one end and a track relay T at the other end, it being understood that this merely represents "the usual means for detecting the presence of -a train and various center fed or cut section track circuits maybe provided as required. 7

The wayside signals-have been conventionally illustrated as the semaphore type, but it is of course understood that other types could be employed such as color light signals of either the individual lighttype or the movable spectacle type, the methods of adaptingthe *control circuits to the different types of signals being A home relay H is pro -'ded for controlling each of the east bound signals SG, which home 'relay' at signals 3SG, 48G and 58G are the conventional neutral type and a distant signal controlling relay D of the usualneutral type is provided at each'signal. A clearing relay=CL employed to initiate operation of the signaling system is provided at each signal location except the signals governing movements into the double track portions such as signals -2SG and 'BSG, which CL relays arej connected in series with the line circuit control for the D relays at the next signal in the rear. 7 a

The signals governing movements into the double track portion are provided with home relays 2H and 6H which arearranged inthe "same manner as the clearing relays CL at the other locations, and the clearing relays CL as well as the two home relays 2H and 6H are provided with two separate windings A and. B. It

is necessary for a proper operation of the present system to provide a certain relation between the resistanceof the windings of the D relays and the WindingsA and B of relays CL, 2H and 61-1, or that is the resistance and the ampere- .turns of the D relays-should be considerably smaller than that of both windings A and B of the CL, 2H and 6H relays, so that when an energizing circuit has been completed connecting windings A and B in series with windings of relay D, the armature of relay D will not be attracted while the armature acted upon by windings A and B will be attracted, and when winding A is shunted the current in this circuit should increase sufiiciently to attract the armature of relay D and the energization of winding A alone should retain its armature. For example, the windings of relay D may be approximately 60 ohms, winding A may be 800 ohms and winding B may be 100 ohms.

. A. directional stick relay S is employed at each of the east bound signal locations except for signals 28G, BSG and 'ISG which stick relays are associated with east-bound train movements, and

.of the portion illustrated in Fig. 1.

inasmuch as certain signaling circuits associated with east-bound train movements are arranged to check the position of the direction relays associated with the opposite traffic direction, certain of the west-bound direction stick relays, namely relays I3S, MS and I5S, have been indicated on the drawings. It will be understood that suitable means is to be employed to protect the signaling circuits against improper alinement of the track switches governingmovements into the passing sidings which has not been shown in the present'disclosure, and that various other expedients well known in the signaling art may be employed as. required but which have been herein omitted as they are not necessary for the understanding of the present invention. In the present system, a source of energy is required for energizing theline circuits, the semaphore signals and the like, which may be a suitable local battery, the oppositeterminals of which have been merely indicated by the symbols and and it is understood that a common or return line wire (not shown) is requiredin ac cordance with the usual practice.

Having now pointed out the essential elements :of the system, itis' believed that the usefulness and the various interrelated functions and 'features of the apparatus and circuits of the present embodiment will be more readily understood by further description being given from the standpoint of operation.

Operation The present system is illustratedin 'a condition wherein no trains are occupying or approaching the railway system illustrated in the present drawings, and in'such a condition, all the apparatus and circuits of the system, with the exception of the track relays T, are deenergized as shown. In theaccompanying drawings, it

will be understood that a complete signaling system arranged in accordance with the present invention includes many single track portions of which the signaling system for the single track portion shown in Fig.1 and Fig. 2 is typical,

and the signaling circuits for each of the single track portions overlap or extend into the ad- 7 jacent portion so that in considering a complete train movement, certain conditions must first be assumed as resulting from a train movement through the portion of the railway system adjacent to that herein illustrated.

In other words, in considering an east bound train movement throughout the illustrated single track portion, it will be understood that the .control circuits for'signal 25G is the same as .thatillustrated forsignal BSG and consequently it will be considered when the present eastbound. train under consideration enters block I, the energizing circuit for the home relay 2H is completed by dropping the track relay IT, although it will be understood later in the description of the initial energization of relay 6H that relay 2H was previously energized by the present train upon entering the portion of the railway system adjacent to the left hand end The present energizing circuit for relay 2H however, may be traced from front contact ID of relay 3T, line wire '2LH, front contact I I of relay 2T, through windingsA and B in series of relay 2H, and :through ,back contact I2 of relay IT ,A circuit is also completed for energizing relays 2D and 30L while the present east-bound train is occupying block I which may be traced from through windings A and B in series of relay 30L, linewire ZLD, through the windings of relay 2D, and through back contact M of relay It will -be-noticed that this circuit includes windings A and B of relay 30L in series with the windings of relay 2D, and as previously stated, the resistance of winding A is sufficiently high to prevent the flow of sufficient current in this circuit to attract the armature of the low resistance relay 2D, but the sameamount of current is effective when flowing throughthe larger number of turns of windings A and B of relay 30L to'attract its armature.

The picking up of relay 30L then ,closes an obvious circuit at its front contact l over'line wire 3LD to, in the same manner, attract the armature of. relay 40L but to allow the armature of relay 3D to remain inits released position, and the picking up of relay 40L likewise completes an obvious circuit at its front contact IE to pick up relay 50L over line wire 4LD- but to allow the armature of relay GD to remain in its released position.

In other words, it will be clear that a train occupying section I causes the successive picking up of all the clearing relays 30L, 40L and 50L, and the picking up of the last clearing relay 50L completes an energizing circuit for the home relay 6H which may be traced from front contact I! of relay 1T, line wire SLH, front contact 18 of relay 6T, through windings A and B in series of relay 6H, line wire 5LD, through the windings of relay 5D and through front contact IQ of relay 5CL to The picking up of the home relay 6H completes an energizing circuit operating the semaphore signal mechanism of signal BSG to a 45 or caution position, which circuit may be traced from front contact 20 of relay BI-I, back contact 2| of relay 6D, 45 control wire 22, through the signal mechanism to A contact 23 operated by the semaphore mechanism at signal GSG is now operated to its 45 position to thereby close an obvious shunt circuit around the winding A of relay 6H, which winding A being of comparatively high resistance results in an increase in current through the windings of relay 5D which is effective to attract its armature and the same amount of current through winding B of relay 6H is still effective to retain its armature. The previous picking up of the last clearing relay V5CL also closed a circuit for energizing the home relay 5H from back contact '25 of the west-bound stick relay I3S, line wire 5LH, front contact 26 of relay 5T, through the winding of relay 5H and through front contact 27 of relay 5CL to An operating circuit is now completed for signal 5SG from back contact 28 of relay 58, front contact 29 of relay 5H, front contact 30 of relay 5D, 90 control wire 3|, through the semaphore mechanism of signal 58G to The signal 5SG is now operated to a 90 or clear position which moves a contact 32 on the semaphore signal mechanism to its 90 position which completes a shunt circuit around high resistance winding A of relay 50L, thereby increasing the current through relay 4D sufiiciently to attract its armature. The previous picking up of relay 5H also completed a circuit for energizing the home relay 4H from front contact 34 of relay 5H, front contact 35 of relay 5CL,

back .contact .36 of thevwest-bound stick relay HS, line wire 4LI-I,-front contact 31 of relay 4T,

of relay 4D, 90 control wire 42, through the semaphore'signal mechanism to The signal 45G is thereby operated to its 90 or clear position which moves a contact on the semaphore signal mechanism to its 90 position, thereby shunting out winding A of relay 40L to increase the current in relay 3D sufliciently to attract its armature. The previous picking up of relay .4H completed a pick up circuit for relay 3H from front contact of'relay 4H, front contact 46 of relay 4CL, back contact 41 of. relay I58, line wire 3LH, front contact 48 of relay 3T, through the windings of relay 31-1 to 1 An operating circuit for the entering signal 38G is now completed from back contact 50 of relay. 38, front contact 5| of relay 3H, front contact 52 of relay 3D, 90 control wire 53, through the semaphore signal mechanism to The entering signal 3SG is now operated to a 90 or clear position which in a similar manner shunts the high resistance winding A of relay 3CL by a semaphore signal contact 54 to pick up relay 2D. An operating circuit for the signal 23G is now completed by front contact 55 of. relay 2H, energized as previously described, and through front contact 56 of relay 2D to the 90 control wire 51, thereby operating signal ZSG to its 90 or clear position.

It will now be clear that a train upon entering block I successively picks up all the clearing relays up to the next-to-the-last signal location in the single track portion, and the picking up of this last clearing relay or relay 5CL, energizes the home relay for the next signal in advance to provide a caution signal indication at this point, and the last clearing relay also picks up its associated home relay, which home relay causes the successive picking up of all the rear home relays back to the entrance to the single track portion. It will also be clear that throughout the single track portion, each D or 45 signal control relay is picked up by the operation of the next signal in advance to a caution or a clear position, thus clearing all the wayside signals throughout the single track portion and allowing the system to thereafter function in a manner similar to that of a conventional normally en ergized system.

When the present east bound train enters block 2, relay 2D is shunted through back contacts I4 and 59' of relays IT and 2T, and relay 30L is maintained energized by back contact 59 of track relay 2T, but the distant relay 2D is later deenergized by the picking up of track relay IT at back contact Hi When the train departs from block I. However, when the present train departs from block 2 and enters block 3, the clearing relay 30L is dropped by the picking up of track relay 2T and the consequent opening of its back contact 59, thereby dropping relay 3D at open front contact I5 of relay 3CL, but the next clearing relay 40L is maintained energized by a back contact 63 of track relay 3T.

It will of course be obvious that the dropping of relay 3T deenergizes the home relay 3H at front contact 48 thereby causing the signal 38G to operate to its stop position while block '3 is occupied. A contact 60 is provided on the semiaphore mechanism of signal 38G and is closed only while-the semaphore arm is moving through an intermediate position for'eirample through its 40 to 30 position and is opened. upon reaching its stop position, which contact 60. closes an obvious energizing circuit for the, directional stick relay 3S while signal 33G is moving to its stop position over the line circuit 3LH andthrough back contact 48 of track relay ST. A stick circuit for relay BS is then completed through back contact SI of relay 3H and stick contact 62 which holds up relay 38 after the semaphore contact has been opened by the completion of the movement of the semaphore arm to its stop position. The clearing relay 4CL is maintained energized by a front contact 54 of the stick relay 38 after track relay 3T picks up, and relayAD is shunted upon the dropping of track relay 4T through back contact 12 and front contact l6.

Theentrance of the present train into block 4 deenergizes the home relay 4H, thus, causing the signal 43G to operate to its stop position, and a contact 66 on the semaphore mechanism operates in a manner similar to thepreviously described semaphore contact 59 at signal 38G to pick up the stick relay 48 over line wire 4LH and through back contact 31. of track relay 4T, and a stick circuit is thereafter effective to hold relay 4S picked'up through back contact 61 of relay 4H and. stick contact 68 The picking up of stick relay 48 now completes an energizing circuit for the rear home signal 3H through its front contact H3 and front contact 46 of relay 4CL which is being held up by the rear stick relay 3S, and thepicking up of the rear home relay 3H obviously drops the stick relay 3S at open back contact BI and the dropping of relay SS in turn releases the clearing relay 40L at open front contact 64 which is then effective to again deenergize the rear home relay 3H. In other words, the picking up of the stick relay 4S momentarily energizes the rear home relay to restoreall of the relays at the rear signal location to their normal deenergized condition.

The dropping of relay 40L opens the energizing circuit for relay 4D which was previously shunted, but the forward clearing relay 5CL is maintained energized through back contact 12 of track relay 4T, and when the present train departs from section 4; a front contact 69 on the stick'relay 48 is effective to still maintain relay ECL picked up. The directional stick relay SS is of course picked up by the entrance of the train into block 5 through semaphore contact l3 and back contact 26 of track relay ET and subsequently held up by a stick circuit including back contact 14 of relay 5H and its stick contact 15. The picking up of stick relay 58 then restores the control relays at the rear signal location to their normal deenergized condition by enjergizing the rear home relay 4H through its front contact ll and front contact 35 of the clearing relay 50L, the energization of relay 4H being effective to release the stickrelay 4S atcontact 61, the releasing of relay 4S dropping the forward clearing relay 50L at front contact 69 and the deenergization of relay 5CL then acting to remove the energization from the rear home relay 4H at front contact 35. The release of relay 5CL opens the energizing circuit forrelay 5D which was previously shunted through back contact 78 and'front contact l9, but the forward home relay GE is maintained energized through back contact 18 of track relay 5T.

In order to restore the control'relays associ- 75 ated with signal 58G to their normal deenergized condition upon the departure of a ,train from block 5, a front contact 16'has been provided upon the stick relay 5S which is effective to, energize relay 5H even though relay 50L is deenergized, and the picking up of relay 5H in turn deenergizes the stick relay 5S at back contact 14-, the dropping of relay BS in turn dropping the home relay SE to restore the control relays at that location to their deenergized condition. The present train progresses eastwardly throughblockfi in a very obvious manner whereupon the clearing of control relays associated with the single track portion joining the right hand end of the portion shown in the accompanying drawings are initiated into operation over the line circuit BLH shown at the bottom of Fig. 2 in the manner previously described. It will be noticed in the description of the previous train movement that the apparatus at each signal location passed by the train was restored to its normal 'deenergized condition by picking up the rear home relay I-I momentarily and inasmuch as it is desirable to reduce the duration of a clear signal indication during such conditions, aback contact of the associated stick relays has been provided in the control. circuit for the signals at these locations, whereby the momentary picking up of the home relays under this condition will not immediately energize the associated signal mechanism inasmuch as the stick relays arepicked up through a portion of this period. Q

The manner in which the present system operates to prevent a train movement into the single track portion' while an opposing train is occupying such portion may be seen by considering how 'a'west-rbound train movement affects the east-bound signal controlling apparatus disclosed in the present drawings. It is obvious that a west-bound train upon entering blocks 6 or 5 does not pick up the clearing relay 5CL so that the home relay 5H cannot be picked up, and as each of the rear home relays includes a front contact of the forward home relay and a front contact of the associated track relay, the home relay 3H cannot pick up and consequently the signal 38G cannot be operated to a clear position while a west-bound train is occupying the illustrated portion of single track. It will also be obvious that a west-bound train movement does not pick up the east directional stick relays inasmuch as the associated semaphore signal mechanisms are in this case assuming their stop positions before the associated trackrelays are dropped, thus pre- 1 venting a completion of the pick up circuits for the stick relays.

The absolute permissive block feature of permittingfollowing train movements in the same direction through the'single track portion is provided in the present system by the directional stick relays in accordance with the usual practice. In other words, while the previously considered east-bound train was occupying section 4, the stick relay 4S was picked up as previously described, so that a second east-bound train entering block I would pick up the clearing relay 3CL which in turn would pick up relay 4CL, thereby completing a circuit forenergizing relay 3H through front contact 10 of relay 4S and front contact 46 of relay 4CL. The home relay 3H thus picking up would operate signal 3SG to its caution positionwhich picks up relay 2D to operate signal 28G to a clear position and allows the second train to proceed into the single track portion. The relay 3D would pick up as soonas the first train enters block to operate signal 4SGto a caution or 45 position and shuntwinding A of relay 40L, thereby operating signal 3SG from its caution to its clear position.

In this manner it will be seen that one train may follow another into the single track portion by first reestablishing the energizing circuits for such clearing relays as have been dropped in the rear of the first train, and the picked up condition of the directional stick relay at the blockoccupied by the first train then allows the home signal controlling relays in the rear of the train which are associated with the particular direction of travel only to be successively energized. The distant signal controlling relays pick up in the same manner as previously described, or by the operation of the semaphore signal mechanism at the next forward signal location to a caution or clear position. The signal controlling relays are all restored to their normal deenergized condition at each location after being passed by the last train in the same manner as described in connection with the first train movement.

An absolute permissive block signaling system has thus been provided wherein all the signal controlling relays are normally deenergized when a train is not occupying or approaching the associated portion of the railway system, and wherein the signals normally display a stop or most restricted indication at such times. The advantage of such a system in regard to the saving of the energy ordinarily required in the usual normally energized system to maintain the signal controlling relays energized while a train is not occupying or approaching the associated portion of the railway system is readily apparent. Among the other advantages of the present system is the reduced possibility of displaying a false-clear signal indication by the sticking of a semaphore signal arm, this being due to the fact that the present system provides normally danger signals whereby the sticking of the semaphore arm would ordinarily occur in its danger position thereby providing a restricted but a safe signal indication.

In describing the present invention, attention has been directed to one specific embodiment thereof, without attempting to point out the various alternate or optional features of construction, or the different organizations or combinations that may be employed. For example, in the simplified disclosure of the present invention the clearing relays associated with a particular direction of train movements pick upin the rear of a train traveling in the opposite direction, which operation is ordinarily not objectional but if desired certain changes which are considered to be entirely within the ability of anyone skilled in the railway signaling art could be made to prevent this unnecessary relay operation.

In other words, the particular embodiment of the present invention has been selected to facilitate in the disclosure thereof rather than to limit the number of forms which it may assume.

What I claim is:

1. In a single track railway signaling, system, wayside signals governing trafiic in each direction over the single track, a normally de-energized clearing relay associated with each signal, means successively energizing the clearing relays associ-' ated with signals governing traffic in either direction upon the approach of a train traveling in such direction, a normally de-energized home signal controlling relay for each signal, means dependentl upon traflicfconditions for successively energizing-the home relays f orsignals governingtrafficin. either direction, upon the energization of direction upon the approachofa .train traveling in such direction, a normally deenergized .home signal controlling relay for each signal, means dependent upon traffic conditions for successively energizing the home relays for all of the. signals governing traffic in either direction upon the en-' ergization of the last clearing relay associated with such trafiic direction, a normally de energized distant signal controlling relay for each signal, means including the energizing circuits for the associated clearing relays forcontrolling each distant relay in accordance With'thecondition of the next forward wayside signal, and directional stick relaymeans for less than all the signals governing traffic in either direction.

3.'In an absolute permissive block signaling system, a semaphore signal, a control relay for the semaphore signal, a track relay for controlling the signal control relay, a directional relay having an energizing circuit including aback contact of the trackrelay and a contact on the.

semaphore signal closed only when the semaphore signal assumes a position intermediate the cau' tion andstop position, and a stick circuit for the directional relay including a back contact of the the next forward signal, a directional stick relay 1 associated with each signal, and an energizing circuit for each directional relay including said front contact of the control relay for the next forward signal, a back contact of the associated track relay and a' contact closed only during transit of the associated semaphore. signal'be tween its caution and stop positions.

5. An absolute-permissive-block single track signaling system comprising, signals for governing traffic in one direction through'a single track section, signals'for governing traflic in the'opposite direction through said single track section, a home relay for each signal, a normally open energizing circuit for each home relay including a front contact of the home relay next in advance, a directional stick relay for each signal whichv if energized closes a contact in the energizing circuit for the home relay next in the rear, and means for sequentially energizing the home relays governing traffic in a particular direction when a train moving. in that direction approaches said single track section. 1

6. An absolute-permissive-block single track signalings'ystem comprising,- signals for governing traflic in one direction through a single track section, signals for governing trafii'c in the opposite directionthr'ough'said single track section, a home relay for each signal, a normally open energizingrcircuit'for each home relay including a front contact of the home relay next in advance, a clearing relay for each signal location, a normally open energizing circuit for each clearing relay controlled through afront contact of the clearing relay for the next signal in the rear, means responsive to a train approaching said section in one direction for causing successive energization of the signal clearing relays governing that direction of traffic, and means responsive to the energization of the last signal clearing relay providing'no train has entered the opposite end of said single track section for causing successive energization of the home relays governing signals for'said one direction, whereby the approach of a train in one direction toward said single track section causes the home relays governing the signals for said one direction to be successively picked up starting with the home relayat the exit end of said. section for said one direction of train travel. r r

7. 'An absolute-permissive-block single track signaling system comprising, signals for governing trafiic in one direction through a single track section, signals for governing trafiic in the opposite direction through said single track section, a home relay for each signal, a normally open energizing circuit for each home relay including a front contact of the home relay next in advance, and means responsive to a train approaching said section in one direction providing no train is approaching said section from the opposite direction for causing successive energization of said home relays starting with the home relay at the exit end of said section for said one direction of train travel.

i 8. An absolute-permissive-block single track signaling system comprising, signals for governing trafiic in one direction through a single track section, signals for governing trafiic in the opposite direction through said single track section, a home relay for each signal, a normally open energizing circuit for each home relayincluding a front contact of the home relay next in advance, means responsive to a train approaching said section in one direction providing no train is approaching said section from the oppositerdirection for causing successive energization of said' home relays starting with the home relay at the exit end of said section for said one direction of train travel, and means for causing the second signal to the rear of a train moving through said section to indicate caution upon entrance of a following train into said section.

' 9. An absolute-permissive-block single track signaling system comprising, signals for governing traffic in one direction through a single track section, signals for governing traflic in, the opposite direction through said single track section, a home relay for each signal, a normally open energizing circuit for each'home relay including a front contact of the home relay next in ad- Vance, means responsive to a train approaching said section in one direction providing no train is approaching said section from the opposite direction for causing successive energization of said home relays starting with the home relay at the exitend of said section for said one direction of train travel, and means including a directional stick relay for each signal for causing the second signal to the rear of a train moving th ough said seotion to indicate caution upon entrance of a following train into said section; r

l0. In an absolute-permissive-bloc'k signaling system, the combination with;a single track section connecting two double track portions, sigrials located at intervals through said section for governing trafiic in one direction through said section, signals located at intervals through said section for governing trailic in the opposite direction through said section, a home relay for each signal, a directional stick relay for each signal, a normally open circuit for each home relayin cluding a front contact of the next home relay in advance and a back contact of a directional stick relay associated with a'signal for governing traific in the opposite direction, and means responsive to a train approaching said section in one direction efiective only if there is no train approaching said section from the opposite direction for causing successive energization of the home relays governing signals for governing traffic in said one direction starting with the home relay atthe exit end of said section for said one direction of travel.

'11. In an' absolute-permissive-block signaling system, the combination with a single track sec-= tion connecting two double track portions, signals located at intervals through said section for governing trafiic in one direction through said section, signals located at intervals through said section for governing trafiic in the opposite direction through said section, a home relay for each signal, a; directional stick relay for each signal, a normally open circuit for each home relay including a front contact of the next home relay in advance and a back contact of a directional stick relay associated with a signal for governing trafficrin the opposite direction, means responsive to a train approaching said section in one direction effective onlyif there is no train approaching said section from the opposite direction for causing successive energization of the home relays governing signals for governing traffic in said one direction starting with the home relay at-the exit end of said section for said one I direction of travel, and means including said directional stick relays for causing the second signal to the rear of a train moving through said section to assume a caution position whena second train follows such train into the said single track section. 7

12. An absolute-permissive-block single track signaling system comprising, signals for governing trafiic in one direction through a single track section, signals for governing traflic in the oppoclearing relay for the next signal in the rear,

said clearing relays for one particular direction of trafiic when energized permitting energization of the home relays for that direction of traflic, and means for successively energizing said clearing relays for a particular direction of traffic- When a train moving in that direction approaches said single track section; RQBERTM. PHINNEYJ 

